U.S. patent number 8,465,115 [Application Number 12/615,038] was granted by the patent office on 2013-06-18 for image recording apparatus and image processing method.
This patent grant is currently assigned to Canon Kabushiki Kaisha. The grantee listed for this patent is Koji Fuse, Takashi Ochiai. Invention is credited to Koji Fuse, Takashi Ochiai.
United States Patent |
8,465,115 |
Fuse , et al. |
June 18, 2013 |
Image recording apparatus and image processing method
Abstract
An image recording apparatus acquires, from image data,
gradation information in a region corresponding to a connected
portion at which recording chips are overlapped with each other,
sets, based on the acquired gradation information, control
information for controlling recording rates of respective recording
elements of a plurality of recording chips that are connected in an
overlapped state, and according to the set control information,
generates, from the image data, dot data for respective recording
elements of the plurality of recording chips that are connected in
the overlapped state.
Inventors: |
Fuse; Koji (Tokyo,
JP), Ochiai; Takashi (Machida, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Fuse; Koji
Ochiai; Takashi |
Tokyo
Machida |
N/A
N/A |
JP
JP |
|
|
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
42164920 |
Appl.
No.: |
12/615,038 |
Filed: |
November 9, 2009 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20100118318 A1 |
May 13, 2010 |
|
Foreign Application Priority Data
|
|
|
|
|
Nov 11, 2008 [JP] |
|
|
2008-288967 |
Oct 23, 2009 [JP] |
|
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2009-244716 |
|
Current U.S.
Class: |
347/14 |
Current CPC
Class: |
H04N
1/1903 (20130101); H04N 1/1934 (20130101); G06K
15/107 (20130101); H04N 1/193 (20130101); B41J
2/2132 (20130101); H04N 1/12 (20130101) |
Current International
Class: |
B41J
29/38 (20060101) |
Field of
Search: |
;347/14 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Martin; Laura
Attorney, Agent or Firm: Canon USA Inc IP Division
Claims
What is claimed is:
1. An image recording apparatus configured to record an image on a
recording medium using a recording head having a plurality of
recording chips that are equipped with recording element arrays,
wherein the recording chips are arranged in a direction parallel to
the recording element arrays, wherein a part of the image on the
recording medium is formed by overlapping images recorded by
connected portions that are parts of the different recording tips,
the image recording apparatus comprising: an acquisition unit
configured to acquire, from image data, gradation information in a
region corresponding to a connected portion; a setting unit
configured to set, based on the gradation information, control
information for controlling recording rates of respective recording
elements of the plurality of recording chips; and a generation unit
configured to, according to the set control information, generate,
from the image data, dot data for respective recording elements of
the plurality of recording chips.
2. The image recording apparatus according to claim 1, wherein the
setting unit is configured to set a mask based on the gradation
information, and wherein the generation unit is configured to
generate the dot data from the input image data and to distribute
the generated dot data, using the set mask, to respective recording
elements of the plurality of recording chips.
3. The image recording apparatus according to claim 1, wherein the
setting unit is configured to set a multi-valued mask based on the
gradation information, and wherein the generation unit is
configured to use the set multi-valued mask to distribute the image
data to respective recording elements of the plurality of recording
chips that are connected in the overlapped state, and to generate,
from the distributed image data, the dot data for respective
recording elements of the plurality of recording chips.
4. The image recording apparatus according to claim 1, wherein the
recording head is configured to perform scanning a plurality of
times in a same region on the recording medium to record an image
thereon, and wherein the generation unit is configured to generate,
from the image data, dot data to be used in each scanning for
respective recording elements of the plurality of recording
chips.
5. The image recording apparatus according to claim 1, wherein the
setting unit is configured to set the recording rates of the
overlapped recording elements to be larger in maximum change amount
in a case where the gradation information indicates a higher
density than in a case where the gradation information indicates a
lower density.
6. The image recording apparatus according to claim 1, wherein the
image recording apparatus is configured to perform recording with a
plurality of coloring materials, wherein the acquisition unit is
configured to acquire the gradation information for each coloring
material, and wherein the setting unit is configured to set the
control information for each coloring material.
7. An image processing method for generating dot data for an image
recording apparatus configured to record an image on a recording
medium using a recording head having a plurality of recording chips
that are equipped with recording element arrays, wherein the
recording chips are in a direction parallel to the recording
element arrays, wherein a part of the image on the recording medium
is formed by overlapping images recorded by connected portions that
are parts of the different recording tips, the image processing
method comprising: acquiring, from image data, gradation
information in a region corresponding to a connected portion;
setting, based on the gradation information, control information
for controlling recording rates of respective recording elements of
the plurality of recording chips; and according to the set control
information, generating, from the image data, dot data for
respective recording elements of the plurality of recording
chips.
8. A non-transitory computer-readable storage medium storing a
program for causing an image recording apparatus to record an image
on a recording medium using a recording head having a plurality of
recording chips that are equipped with recording element arrays,
wherein the recording chips are in a direction parallel to the
recording element arrays, wherein a part of the image on the
recording medium is formed by overlapping images recorded by
connected portions that are parts of the different recording tips,
the program comprising: computer-executable instructions for
acquiring, from image data, gradation information in a region
corresponding to a connected portion; computer-executable
instructions for setting, based on the gradation information,
control information for controlling recording rates of respective
recording elements of the plurality of recording chips; and
computer-executable instructions for, according to the set control
information, generating, from the image data, dot data for
respective recording elements of the plurality of recording
chips.
9. An image recording apparatus configured to record an image on a
recording medium using a plurality of recording chips, wherein a
part of the image on the recording medium is formed by overlapping
images recorded by connected portions that are parts of the
different recording chips, the image recording apparatus
comprising: an acquisition unit configured to acquire, from image
data, gradation information in a region corresponding to a
connected portion; a setting unit configured to set, based on the
gradation information, control information for controlling
recording of respective recording elements of the plurality of
recording chips; and a generation unit configured to, according to
the set control information, generate, from the image data, dot
data for respective recording elements of the plurality of
recording chips.
10. The image recording apparatus according to claim 9, wherein the
setting unit is configured to set a mask based on the gradation
information, and wherein the generation unit is configured to
generate the dot data from the input image data and to distribute
the generated dot data, using the set mask, to respective recording
elements of the plurality of recording chips.
11. The image recording apparatus according to claim 9, wherein the
setting unit is configured to set a multi-valued mask based on the
gradation information, and wherein the generation unit is
configured to use the set multi-valued mask to distribute the image
data to respective recording elements of the plurality of recording
chips that are connected in the overlapped state, and to generate,
from the distributed image data, the dot data for respective
recording elements of the plurality of recording chips.
12. The image recording apparatus according to claim 9, wherein the
recording head is configured to perform scanning a plurality of
times in a same region on the recording medium to record an image
thereon, and wherein the generation unit is configured to generate,
from the image data, dot data to be used in each scanning for
respective recording elements of the plurality of recording
chips.
13. The image recording apparatus according to claim 9, wherein the
setting unit is configured to set the recording rates of the
overlapped recording elements to be larger in maximum change amount
in a case where the gradation information indicates a higher
density than in a case where the gradation information indicates a
lower density.
14. The image recording apparatus according to claim 9, wherein the
image recording apparatus is configured to perform recording with a
plurality of coloring materials, wherein the acquisition unit is
configured to acquire the gradation information for each coloring
material, and wherein the setting unit is configured to set the
control information for each coloring material.
15. An image recording method for recording an image on a recording
medium using a plurality of recording chips, wherein a part of the
image on the recording medium is formed by overlapping images
recorded by connected portions that are parts of the different
recording chips, the method comprising: acquiring, from image data,
gradation information in a region corresponding to a connected
portion; setting, based on the gradation information, control
information for controlling recording of respective recording
elements of the plurality of recording chips; and according to the
set control information, generating, from the image data, dot data
for respective recording elements of the plurality of recording
chips.
16. A non-transitory computer-readable storage medium storing a
program for causing an image recording apparatus to record an image
on a recording medium using a plurality of recording chips, wherein
a part of the image on the recording medium is formed by
overlapping images recorded by connected portions that are parts of
the different recording chips, the program comprising:
computer-executable instructions for acquiring, from image data,
gradation information in a region corresponding to a connected
portion; computer-executable instructions for setting, based on the
gradation information, control information for controlling
recording of respective recording elements of the plurality of
recording chips; and computer-executable instructions for according
to the set control information, generating, from the image data,
dot data for respective recording elements of the plurality of
recording chips.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording head that includes a
plurality of recording chips equipped with recording element
arrays, wherein the plurality of recording chips are partly
overlapped and mutually connected in a direction parallel to the
recording element arrays. When an image recording apparatus records
an image on a recording medium, the image recording apparatus
generates dot data for the recording head.
2. Description of the Related Art
Image recording apparatuses are generally configured to record
images (including characters and marks) on recording media (e.g.,
sheets) based on recording information. The image recording
apparatuses can be classified into an inkjet type, a wire dot type,
a thermal type, a laser beam type, or another type, according to
the type of recording.
An inkjet type recording apparatus (i.e., an inkjet recording
apparatus) includes an inkjet recording head (hereinafter, simply
referred to as a "recording head"), which can serve as a recording
unit. The recording head has recording elements that can discharge
ink toward a recording medium to record an image.
A serial type inkjet recording apparatus can perform a recording
operation with a recording head that performs scanning in a main
scanning direction perpendicular to a conveyance direction of a
recording medium (i.e., a sub scanning direction). The serial type
inkjet recording apparatus causes a recording head to move along a
recording medium to record an image on the recording medium.
More specifically, each time when the recording head finishes a
recording operation corresponding to one complete main scanning,
the serial type inkjet recording apparatus conveys the recording
medium by a predetermined amount in the sub scanning direction. The
serial type inkjet recording apparatus repeats the above-described
operation to complete the recording on the entire region of the
recording medium.
A full line type inkjet recording apparatus includes a recording
head whose recording width is comparable to the width of a
recording medium. The full line type inkjet recording apparatus is
configured to continuously perform a recording operation for one
complete line without moving the recording head, while conveying
the recording medium. The full line type inkjet recording apparatus
is advantageous in speedily accomplishing image formation
processing, and can be adequately used as a recording apparatus
dedicated to the on demand type recording services, whose needs are
recently increasing, for example, as discussed in Japanese Patent
Application Laid-Open No. 2002-292859.
However, in manufacturing the recording head to be incorporated in
the above-described full line type recording apparatus, it is
difficult to accurately produce all of the inkjet recording
elements without any defects, so as to be sequentially disposed in
a long length comparable to the entire width of a recording region
of a recording medium.
For example, when the full line type recording apparatus performs
recording on a sheet of A3 size paper so as to realize a resolution
level of 1200 dpi, a full line type recording head is required to
include approximately 14 thousands of recording elements
(approximately 280 mm in recording width). It is generally
difficult to manufacture all of such numerous recording elements
without any defects. Even if the manufacturing of the
above-described recording head can be successfully accomplished, an
efficiency percentage may be low and manufacturing costs may
increase.
For the reasons described above, a long connected head is proposed
as a prospective full line type recording head. The connected head
is a recording head including a plurality of recording element
arrays, each including a plurality of recording elements, which are
continuously or sequentially disposed in the direction parallel to
the recording element arrays.
More specifically, the connected head is a recording head including
a plurality of short heads (i.e., the heads used in the
above-described serial type inkjet recording apparatus), which are
connected in the direction parallel to the recording element arrays
to realize an elongated head configuration. Similarly, the serial
type recording apparatus can use a long recording head to perform
recording if the long recording head can be realized by the
above-described connecting configuration.
However, an image generated by the connected head may include
undesirable streaks in a region corresponding to a connected
portion extending between two recording element arrays where edges
of two recording element arrays are overlapped with each other. In
general, such undesirable streaks appear in an image region
corresponding to a connected portion extending between two
recording element arrays when an impact position of a coloring
material recorded by a recording element array deviates from a
correct position. For example, the impact position of a coloring
material deviates from the correct position when the mounting
location of a recording element array deviates from a predetermined
position, or when the recording element array is mounted in an
inclined state (i.e., when the recording head is mounted in an
inclined state).
FIG. 1 illustrates a positional relationship between a recording
head 101, which is in an ideal state where no deviation occurs in
impact position of ink, and a dot layout pattern that can be
recorded by respective recording element arrays (i.e., a first
recording element array 102 and a second recording element array
103). A right-side schematic illustration in FIG. 1 is an example
pattern of ideal dots that do not generate any streaks appearing in
an image region corresponding to a connected portion extending
between two recording element arrays.
In FIG. 1, a direction X indicates a conveyance direction of a
recording medium and a direction Y indicates a direction
perpendicular to the direction X. Each of the recording element
arrays constituting the recording head 101 (i.e., the first
recording element array 102 and the second recording element array
103) extends in the direction Y. In general, the size of each dot
is sufficiently large so that neighboring dots can be overlapped
with each other. However, for the sake of convenience, the dots
illustrated in FIG. 1 are smaller ones.
On the other hand, FIG. 2 illustrates an example pattern of dots in
a case where amounting location of the second recording element
array 103 deviates from the ideal position, according to which
streaks are generated in an image region corresponding to a
connected portion extending between two recording element arrays
due to a deviation in ink impact position caused by the mounting
deviation of the second recording element array 103.
In FIG. 2, the mounting location of the second recording element
array 103 relative to the first recording element array 102 is
shifted from an ideal position toward a positive direction in the
direction Y. Therefore, the density of dots decreases in the image
region corresponding to the connected portion extending between two
recording element arrays. In other words, white streaks appear in
the image region corresponding to the connected portion extending
between two recording element arrays.
FIG. 3 illustrates an example pattern of dots in a case where the
recording head 101 is inclined, according to which streaks are
generated in an image region corresponding to a connected portion
extending between two recording element arrays due to a deviation
in ink impact position. In FIG. 3, the recording head 101 is
inclined in the clockwise direction relative to the vertical
direction of an XY plane.
As a result, direction Y positions of the dots recorded by the
second recording element array 103 are shifted toward a positive
direction relative to direction Y positions of the dots recorded by
the first recording element array 102. Therefore, the dot density
decreases in an image region corresponding to a connected portion
extending between two recording element arrays. In other words,
white streaks appear in the image region corresponding to the
connected portion extending between two recording element
arrays.
There are some conventional methods available to prevent the
above-described streaks from appearing in an image region
corresponding to a connected portion extending between two
recording element arrays. For example, a conventional method for
accurately arranging the recording chips in the connected portion
is available. This method can reduce a deviation in pitch of
respective recording elements.
Further, there is another conventional method for reducing or
weakening the streaks appearing in the image region corresponding
to the connected portion extending between two recording element
arrays by controlling the number of dots to be recorded by each
recording element array that constitutes the connected portion as
illustrated in FIG. 1.
However, if the chip arrangement in the connected portion is
accurately performed, manufacturing costs increase significantly.
Further, if a correction is performed by appropriately increasing
or reducing the number of recording dots to be used by each
recording element array that constitutes the connected portion, it
is necessary to individually determine an appropriate correction
amount according to each gradation for all pixels. Therefore, a
complicated configuration is required.
SUMMARY OF THE INVENTION
Exemplary embodiments of the present invention are directed to an
image recording apparatus that can prevent undesirable streaks from
being generated in an image region corresponding to a connected
portion extending between two recording element arrays when the
image recording apparatus records an image with a long recording
head including a plurality of recording chips that are connected
with each other.
According to an aspect of the present invention, an image recording
apparatus is configured to record an image on a recording medium
using a recording head having a plurality of recording chips that
are equipped with recording element arrays, wherein the recording
chips are partly overlapped and are connected in a direction
parallel to the recording element arrays. The image recording
apparatus includes an acquisition unit configured to acquire, from
image data, gradation information in a region corresponding to a
connected portion at which the recording chips are overlapped with
each other, a setting unit configured to set, based on the
gradation information, control information for controlling
recording rates of respective recording elements of the plurality
of recording chips that are connected in an overlapped state, and a
generation unit configured to, according to the set control
information, generate, from the image data, dot data for respective
recording elements of the plurality of recording chips that are
connected in the overlapped state.
Further features and aspects of the present invention will become
apparent from the following detailed description of exemplary
embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute
a part of the specification, illustrate exemplary embodiments,
features, and aspects of the invention and, together with the
description, serve to explain the principles of the invention.
FIG. 1 is a schematic view illustrating a positional relationship
between a recording head, which is in an ideal state where no
deviation occurs in impact position, and a dot layout pattern that
can be recorded by respective recording element arrays.
FIG. 2 is a schematic view illustrating an example of a dot pattern
in a case where streaks are generated in an image region
corresponding to a connected portion extending between two
recording element arrays due to a deviation in ink impact position
that may be caused by the deviation of amounting location of the
second recording element array.
FIG. 3 is a schematic view illustrating an example of a dot pattern
in a case where streaks are generated in an image region
corresponding to a connected portion extending between two
recording element arrays due to a deviation in ink impact position
that may be caused by the inclination of the recording element
arrays.
FIG. 4 is a perspective view illustrating an example of a
configuration of principal parts that constitute an inkjet type
line printer according to a first exemplary embodiment of the
present invention.
FIG. 5 is a see-through view illustrating a detailed configuration
of a recording head according to the first exemplary
embodiment.
FIG. 6 is a schematic view illustrating a detailed configuration of
a connected portion extending between two recording chips.
FIG. 7 is a schematic view illustrating a positional relationship
between a recording head and connection masks according to the
first exemplary embodiment, and an example configuration of the
connection masks.
FIG. 8 is a schematic view illustrating an example of a recording
medium, which is divided into a plurality of regions to which one
set of connection masks can be applied.
FIG. 9 is a block diagram illustrating an example of a
configuration of a control system for an inkjet recording apparatus
according the first exemplary embodiment.
FIG. 10 illustrates three types of connection masks that are
different in recording rate in the connected portion.
FIG. 11 is a characteristic view illustrating measurement results
with respect to the visibility of streaks appearing in an image
region corresponding to a connected portion extending between two
recording element arrays.
FIG. 12 is a schematic view illustrating examples of streaks that
have appeared in an image region corresponding to a connected
portion extending between two recording element arrays.
FIG. 13 is a flowchart illustrating an example of a procedure of
image data processing according to the first exemplary
embodiment.
FIG. 14 is a schematic view illustrating a positional relationship
between a recording head and connection masks according to a second
exemplary embodiment of the present invention, and an example
configuration of the connection masks.
FIG. 15 is a block diagram illustrating an example of a
configuration of a control system for an inkjet recording apparatus
according to the second exemplary embodiment.
FIG. 16 is a flowchart illustrating an example of a procedure of
image data processing according to the second exemplary
embodiment.
FIG. 17 is a see-through view illustrating an example of a
configuration of a serial type inkjet recording apparatus according
to a third exemplary embodiment of the present invention.
FIG. 18 is a block diagram illustrating an example of a
configuration of a control system for an inkjet recording apparatus
according to the third exemplary embodiment.
FIG. 19 is a flowchart illustrating an example of a procedure of
image data processing according to the third exemplary
embodiment.
FIG. 20 is a block diagram illustrating an example of a
configuration of a control system for an inkjet recording apparatus
according to a fourth exemplary embodiment of the present
invention.
FIG. 21 is a flowchart illustrating an example of a procedure of
image data processing according to the fourth exemplary
embodiment.
DESCRIPTION OF THE EMBODIMENTS
Various exemplary embodiments, features, and aspects of the
invention will be described in detail below with reference to the
drawings.
FIG. 4 is a perspective view illustrating an example of a
configuration of principal parts of an inkjet recording apparatus
401 according to a first exemplary embodiment of the present
invention. The recording apparatus 401 includes a recording head
(i.e., a full line recording head) 402 that is disposed in a long
range comparable to the entire width of a recording medium, such as
a recording medium P (e.g., a continuous sheet), and can discharge
ink onto the surface of the recording medium P.
The recording head 402 includes a plurality of recording element
arrays fixed thereon. Each recording element constituting a
recording element array can discharge an ink droplet toward the
recording medium P at predetermined timing.
The recording apparatus 401 further includes a plurality of
conveyance rollers 403 and discharge rollers 404. When the
conveyance rollers 403 and the discharge rollers 404 are driven by
a driving motor (not illustrated), the recording medium P can be
conveyed in a direction indicated by arrow VS.
FIG. 5 is a see-through view illustrating a detailed configuration
of the recording head 402 illustrated in FIG. 4. The recording head
402 is a recording head having an elongated shape. The recording
head 402 includes a plurality of recording chips 501, 502, 503,
504, 505, and 506 that are disposed to be connected in a
longitudinal direction thereof. Each recording chip includes four
recording element arrays that are disposed in parallel with each
other to constitute four rows A to D.
The recording element array that constitutes the row A can be used
to perform recording with a black ink. The recording element array
that constitutes the row B can be used to perform recording with a
cyan ink. The recording element array that constitutes the row C
can be used to perform recording with a magenta ink. The recording
element array that constitutes the row D can be used to perform
recording with a yellow ink.
The recording element arrays of the recording chips 501 to 506 are
partly overlapped in a direction parallel to the longitudinal
direction of each recording chip. In the following description, a
recording head including a plurality of recording chips
sequentially disposed thereon is referred to as a connected
head.
FIG. 6 is a schematic view illustrating a detailed configuration of
a connected portion laterally extending between the recording chip
501 and the recording chip 502 illustrated in FIG. 5. The connected
portion extending between two recording chips 501 and 502
illustrated in FIG. 6 is one of a plurality of connected portions
provided on the recording head 402.
Each of four recording element arrays A to D, which cooperatively
constitute a single recording chip, includes one thousand and
twenty-four recording elements 601 that are sequentially disposed
to realize a resolution level of 1200 dpi. Further, the length of
the connected portion along which two recording chips 501 and 502
are overlapped with each other is equivalent to forty recording
elements. FIG. 6 includes an expression " . . . " that represents
recording elements whose illustrations are omitted because all of
numerous recording elements cannot be thoroughly illustrated in a
limited space on the drawing plane.
In the present exemplary embodiment, four recording elements of the
recording chip 501 and four recording elements of the recording
chip 502 are aligned straight on the same recording line in the
connected portion where the recording chips 501 and 502 are
overlapped with each other. However, the arrangement of the
recording elements of two recording chips 501 and 502 is not
limited to the arrangement illustrated in FIG. 6.
For example, another configuration available for the recording
elements of two recording chips 501 and 502 can double the
recording resolution in the connected portion by mutually shifting
the recording elements by a half pitch. Yet, another configuration
available for the recording elements of two recording chips 501 and
502 can be a specific configuration that can realize a resolution
variable depending on the position of respective recording elements
in the connected portion.
Further, the resolution according to which a plurality of recording
elements are disposed, the number of a plurality of recording
elements to be assembled as a recording element array, and the
number of a plurality of recording elements to be overlapped in the
connected portion can be arbitrarily determined.
In the following description, a portion where recording element
arrays are overlapped with each other is referred to as a connected
portion. A portion other than the connected portion is referred to
as a non-connected portion. An example of image processing for the
connected portion is described below.
When a binary dot layout pattern is recorded with the connected
head, it is useful to distribute the dot layout pattern to be
recorded in the connected portion to each recording element array
that constitutes the connected portion illustrated in FIG. 1.
In the present exemplary embodiment, the dot layout pattern to be
recorded in the connected portion can be distributed to respective
recording element arrays through mask processing using mask
patterns (hereinafter, referred to as connection masks) that are
constructed by binary (i.e., "1" or "0") data. The mask processing
to be performed in the present exemplary embodiment is processing
for obtaining a logical AND of the dot layout pattern configured by
binary ("1" or "0") data and the connection mask.
FIG. 7 illustrates a positional relationship between a recording
head and connection masks and an example configuration of the
connection masks. A recording head 801 includes a first recording
element array 802 and a second recording element array 803.
A connection mask 804 is a connection mask for the first recording
element array 802. A connection mask 805 is a connection mask for
the second recording element array 803. In FIG. 7, the direction X
indicates a conveyance direction of a recording medium and the
direction Y indicates a direction along which each recording
element array extends straight.
For the sake of convenience, each recording element array
illustrated in FIG. 7 includes a smaller number of recording
elements. More specifically, each recording element array includes
48 recording elements, and 16 recording elements are allocated to
the connected portion.
The size of each connection mask is 16 pixels in the direction X
and 48 pixels in the Y direction. A combination of the connection
mask 804 and the connection mask 805 (i.e., one set of connection
masks) can be used to perform mask processing for distributing a
dot layout pattern in the same region of a recording medium.
To simplify the following description, a recording head described
below performs recording with a single coloring material. However,
in a case where a recording head can use a plurality of coloring
materials (see FIG. 5) for recording, the above-described
distribution processing using the connection masks is performed for
each coloring material.
FIG. 8 is a schematic view illustrating the entire region of a
recording medium 901, which is divided into a plurality of regions
to which the combination of the connection mask 804 and the
connection mask 805 (i.e., one set of connection masks) illustrated
in FIG. 7 can be applied.
More specifically, each of five regions A to E illustrated in FIG.
8 is a region to which the above-described one set of connection
masks can be applied. The size of each region is 16 pixels in the
direction X and 80 pixels in the direction Y. As illustrated in
FIG. 8, in a case where the size of a recording region is larger
than the size of the connection masks, the connection masks can be
periodically and repetitively applied to the entire recording
region.
In this case, the connection masks to be applied to respective
regions A to E can be varied in mask pattern. For example, in a
case where three types of connection masks (e.g., a connection mask
"a", a connection mask "b", and a connection mask "c"), which are
different in binary ("1" and "0") pattern in the connected portion,
are provided, the connection mask "a" can be applied to the region
A, the connection mask "b" can be applied to the region B, and the
connection mask "c" can be applied to the remaining regions C to
E.
Next, a recording rate of each recording element, which is
dependent on a mask pattern of each connection mask, is described
below. The recording rate of each recording element can be
determined based on the data "1", which is present in a direction
perpendicular to the recording element array in the connection
mask. For example, in FIG. 7, the recording rates of recording
elements in a non-connected portion are 100% because the data
existing in the direction X (i.e., the direction perpendicular to
the recording element array) is all "1."
On the other hand, in FIG. 7, the recording rates of recording
elements in the connected portion are less than 100% because the
data existing in the direction X (i.e., the direction perpendicular
to the recording element array) is a mixture of two pieces of data
("1" and "0"). Further, in FIG. 7, the connection mask 804 for the
first recording element array and the connection mask 805 for the
second recording element array are in a mutually exclusive
relationship with respect to their patterns in the connected
portion. Therefore, the sum of a recording rate by the connection
mask 804 and a recording rate by the connection mask 805 is equal
to 100%.
FIG. 9 is a block diagram illustrating an example of a
configuration of a control system for the inkjet recording
apparatus according to the first exemplary embodiment.
An image data input unit 1001 can input multi-valued image data
from an image input device, such as a scanner or a digital camera.
The image data input unit 1001 can further input multi-valued image
data from a hard disk of a personal computer. An operation unit
1002 is equipped with various keys that can be operated by a user
to perform setting of various parameters and instruct starting a
recording operation.
A central processing unit (CPU) 1003 can control various operations
to be performed by the recording apparatus according to various
programs stored in a storage medium 104. A random access memory
(RAM) 1005 can be used as a work area for various programs stored
in the storage medium 1004, a temporary save area in error
processing, and a work area in image processing.
An image recording unit 1007 can generate a driving signal to be
supplied to a recording element so that each dot can be printed at
a desired position based on a binary dot layout pattern generated
by an image data processing unit 1006. A bus line 1008 can transmit
address signals, data, and control signals that are used or
processed in the apparatus. The storage medium 1004 stores control
programs and connection mask data.
The storage medium 1004 includes a control program group storage
unit 1004a, a connection mask storage unit 1004b, and a mask
information storage unit 1004c. The control program group storage
unit 1004a can store various programs that can be used to control
the recording apparatus according to the present exemplary
embodiment.
The connection mask storage unit 1004b can store a plurality of
connection masks that are mutually different in mask pattern. In
the present exemplary embodiment, the connection mask storage unit
1004b stores a plurality of connection masks that are different in
recording rate. The number of the connection masks stored in the
connection mask storage unit 1004b can be arbitrarily determined.
In the present exemplary embodiment, the connection mask storage
unit 1004b stores three connection masks (i.e., the connection mask
"a", the connection mask "b", and the connection mask "c").
FIG. 10 illustrates recording rates of the connection mask "a", the
connection mask "b", and the connection mask "c" for each of the
recording element arrays 1 and 2. These three connection masks are
different in maximum change amount of the recording rate in the
direction parallel to the recording element array.
In FIG. 10, the abscissa axis of each graph represents the position
of each recording element and the ordinate axis of each graph
represents the recording rate. In the present exemplary embodiment,
the maximum change amount of the recording rate is a maximum
inclination amount in each graph of FIG. 10. The connection mask
"c" is superior to the connection mask "b" in the maximum change
amount of the recording rate. Further, the connection mask "b" is
superior to the connection mask "a" in the maximum change amount of
the recording rate.
The mask information storage unit 1004c can store measurement
results with respect to the visibility of streaks appearing in an
image region corresponding to a connected portion extending between
two recording element arrays, which can be generated when the
plurality of mask patterns stored in the connection mask storage
unit 1004b are used to record, with each coloring material, a
plurality of pieces of test image data that are different in
gradation.
FIG. 11 illustrates evaluation results with respect to the
visibility of streaks appearing in an image region corresponding to
a connected portion extending between two recording element arrays
in a case where the above-described three types of connection masks
stored in the connection mask storage unit 1004b are used to
record, with a coloring material K, a plurality of pieces of test
image data that are different in gradation level. The test image
data is monochromatic multi-valued image data, which is
color-separated so as to correspond to each ink color. The
gradation level is uniform regardless of the location on an
image.
In FIG. 11, the abscissa axis represents the gradation level of
test image data and the ordinate axis represents the visibility of
streaks that appear in an image region corresponding to a connected
portion extending between two recording element arrays when the
test image data is recorded on a recording medium. According to the
evaluation result illustrated in FIG. 11, the lightness is higher
as the gradation level is higher. The visibility of streaks has a
larger value as stronger streaks appear in an image region
corresponding to a connected portion extending between two
recording element arrays.
In the evaluation, a plurality of persons can determine a
visibility level of streaks appearing in an image region
corresponding to a connected portion extending between two
recording element arrays based on their own decisions when they
have checked an image recorded on a recording medium.
Further, it is useful to obtain a quantized value representing the
visibility of streaks appearing in an image region corresponding to
a connected portion extending between two recording element arrays,
which can be, for example, obtained by evaluating an average
density of a recorded image in the direction parallel to the
recording element array. The visibility of streaks appearing in the
image region corresponding to the connected portion illustrated in
FIG. 11 is a result obtained based on an average density of the
image recorded on a recording medium in the direction parallel to
the recording element array.
FIG. 12 is a schematic view illustrating examples of the streaks
appearing in an image region corresponding to a connected portion
extending between two recording element arrays that can be observed
in a case where the masks a, b, and c are used to record, with the
coloring material K, test image data belonging to a gradation
region .alpha. (gradation level=32/255), a gradation region .beta.
(gradation level=96/255), and a gradation region .gamma. (gradation
level=160/255).
In the present exemplary embodiment, a gradation level indicated by
0 corresponds to the maximum density and a gradation level
indicated by 255 corresponds to the minimum density (i.e., a level
comparable to white paper). It is understood from FIGS. 11 and 12
that the streaks appearing in the image region corresponding to the
connected portion can be minimized in a case where the connection
mask "c" is used in the gradation region .alpha., and in a case
where the connection mask "b" is used in the gradation region
.beta., and further in a case where the connection mask "a" is used
in the gradation region .gamma..
The examples illustrated in FIGS. 11 and 12 are based on the
recording performed with the coloring material K. However, in
addition to the information relating to the coloring material K,
the mask information storage unit 1004c stores information relating
to other coloring materials C, M, and Y with respect to the
visibility of streaks appearing in an image region corresponding to
a connected portion extending between two recording element
arrays.
The image data processing unit 1006 can perform various image
processing (e.g., color matching processing and color separation
processing) on RGB multi-valued data input by the image data input
unit 1001. Then, the image data processing unit 1006 can generate a
binary dot layout pattern to be recorded by respective recording
elements of the connected head. The image data processing unit 1006
includes a color matching processing unit 1006a, a color separation
processing unit 1006b, a gradation information acquisition
processing unit 1006c, a connection mask selection processing unit
1006d, a binarization processing unit 1006e, and a connected
portion data distribution processing unit 1006f.
An example of image data processing that can be performed by the
image data processing unit 1006 is described below with reference
to a flowchart illustrated in FIG. 13.
In step S1401, the color matching processing unit 1006a maps the
multi-valued RGB data input by the image data input unit 1001 into
color gamuts that are reproducible by the image recording
apparatus. Then, the color matching processing unit 1006a generates
multi-valued R', G', and B' data.
In step S1402, the color separation processing unit 1006b generates
multi-valued CMYK data that indicates discharge amounts of
respective inks based on the multi-valued R', G', and B' data. The
color matching processing and the color separation processing are
conventionally known although not described in detail in the
present embodiment.
In step S1403, the gradation information acquisition processing
unit 1006c obtains, for each coloring material, an average value of
the multi-valued CMYK data in the connected portion as gradation
information in each region (i.e., each of the regions A to E
illustrated in FIG. 8) to which one set of connection masks can be
applied. More specifically, the gradation information acquisition
processing unit 1006c calculates an average value of image data
corresponding to the connected portion for C, M, Y, and K in each
of the regions A to E.
Next, in step S1404, the connection mask selection processing unit
1006d performs processing for setting connection masks based on the
gradation information as control information for controlling
recording rates of respective coloring materials in each region.
More specifically, the connection mask selection processing unit
1006d selects a connection mask corresponding to each coloring
material of each region from a plurality of masks stored in the
connection mask storage unit 1004b, based on an average value of
each coloring material, referring to the information stored in the
mask information storage unit 1004c, so that the streaks appearing
in a recorded image region corresponding to the connected portion
can be reduced or weakened.
An example of the processing to be performed by the connection mask
selection processing unit 1006d is described below with reference
to FIGS. 8 and 11. For example, if an average value of the coloring
material K in the connected portion of the region A illustrated in
FIG. 8 is in the gradation region .gamma. illustrated in FIG. 11,
the connection mask selection processing unit 1006d selects the
connection mask "a" for the coloring material K in the region A.
Further, in a case where an average value of the coloring material
K in the connected portion of the region B is in the gradation
region .beta., the connection mask selection processing unit 1006d
selects the connection mask "b" for the coloring material K in
region B.
Moreover, in a case where an average value of the coloring material
K in the connected portion of respective regions C to E is in the
gradation region .alpha., the connection mask selection processing
unit 1006d selects the connection mask "c" for the coloring
material K in respective regions C to E. Similarly, the connection
mask selection processing unit 1006d selects a connection mask for
each of other coloring materials C, M, and Y referring to an
average value in the connected portion of each region.
In step S1405, the binarization processing unit 1006e binarizes the
multi-valued CMYK data according to an error diffusion method or a
dither method. The binarization processing unit 1006e generates a
binary dot layout pattern that indicates discharge or non-discharge
of ink.
In step S1406, the connected portion data distribution processing
unit 1006f distributes the dot layout pattern, using the selected
mask, to respective recording elements of a plurality of recording
element arrays that correspond to the connected portion. Then, the
connected portion data distribution processing unit 1006f generates
a binary dot layout pattern to be recorded by the recording
elements of each recording element array that constitute the
connected head.
As described above, the image recording apparatus according to the
first exemplary embodiment can prevent or reduce undesirable
streaks from being generated in an image region corresponding to a
connected portion extending between two recording element arrays to
attain a goal of obtaining high-quality recorded images while
realizing speedy recording processing.
Similar to the first exemplary embodiment, a second exemplary
embodiment of the present invention can be realized by the inkjet
recording apparatus illustrated in FIG. 4. A configuration similar
to that described in the first exemplary embodiment is not
described below. A configuration different from that described in
the first exemplary embodiment is described below.
Connection masks to be used in the present exemplary embodiment are
different from the binary masks described in the first exemplary
embodiment. The connection masks according to the present exemplary
embodiment are multi-valued masks that can distribute input
multi-valued data to a plurality of recording element arrays that
constitute the connected portion.
The connection mask to be used in the present exemplary embodiment
can be constructed by any data that can be represented by real
numbers in a range from "0" to "1." Mask processing according to
the present exemplary embodiment includes obtaining a product of a
multi-valued mask and color separated multi-valued image data to
generate distribution-completed multi-valued data corresponding to
the plurality of recording element arrays that constitute the
connected portion. When the data value is "0", it means that the
recording to be performed is nothing. When the data value is "1",
it means that the recording to be performed is perfect. The
above-described connection masks can be referred to as multi-valued
connection masks.
FIG. 14 is a schematic view illustrating a positional relationship
between the recording head 801 and multi-valued connection masks
and an example configuration of a pair of multi-valued connection
masks according to the present exemplary embodiment. The example
illustrated in FIG. 14 is a combination of a connection mask 1501
for the first recording element array 802 and a connection mask
1502 for the second recording element array 803.
The recording rate of each recording element can be determined
based on values of data that are present in the direction X (i.e.,
in the direction perpendicular to the recording element array) of
the connection mask. The recording rates of recording elements in a
non-connected portion are 100% because the data present in the
direction X (i.e., in the direction perpendicular to the recording
element array) is all "1."
On the other hand, the recording rates of recording elements in the
connected portion are less than 100% because the data present in
the direction perpendicular to the recording element array is real
numbers in the range from "0" to "1." Further, in the connected
portion, the sum of a recording rate by the connection mask 1501
for the first recording element array 802 and a recording rate by
the connection mask 1502 for the second recording element array 803
is equal to 100%.
FIG. 15 is block diagram illustrating an example of a configuration
of a control system for the inkjet recording apparatus according to
the second exemplary embodiment. A connection mask storage unit
2201 can store multi-valued connection masks. A mask information
storage unit 2202 can store information representing the visibility
of streaks appearing in an image region corresponding to a
connected portion extending between two recording element arrays in
a case where the multi-valued connection masks are used to perform
recording.
Further, a connection mask selection processing unit 2203 can
select a multi-valued connection mask. A connected portion data
distribution processing unit 2204 can distribute multi-valued CMYK
data. The rest of the configuration illustrated in FIG. 15 is
similar to the corresponding part of the first exemplary embodiment
described with reference to FIG. 9.
FIG. 16 is a flowchart illustrating an example of image data
processing according to the second exemplary embodiment. The
flowchart illustrated in FIG. 16 is different from the flowchart
descried in the first exemplary embodiment in that the connected
portion data distribution processing and the binarization
processing are switched in the execution order. The rest of the
flowchart illustrated in FIG. 16 is similar to the corresponding
part of the flowchart according to the first exemplary embodiment
illustrated in FIG. 13.
In step S1605, the connected portion data distribution processing
unit 1006f performs processing for obtaining a product of the
multi-valued connection mask selected in step S1404 and the
multi-valued CMYK data generated by the color separation processing
unit 1006b (see step S1402) to generate multi-valued distribution
data for each of a plurality of recording element arrays.
In step S1606, the binarization processing unit 1006e binarizes the
multi-valued distribution data to generate binary data for each
recording element array.
As described above, the image recording apparatus according to the
second exemplary embodiment can prevent or reduce undesirable
streaks from being generated in an image region corresponding to a
connected portion extending between two recording element arrays to
attain a goal of obtaining high-quality recorded images while
realizing speedy recording processing.
The recording apparatus described in the first exemplary embodiment
is the full line type inkjet recording apparatus that has a long
recording region comparable to the entire surface of a recording
medium. A third exemplary embodiment of the present invention is
based on a serial type inkjet recording apparatus that includes a
carriage capable of discharging ink onto a recording medium while
moving in the main scanning direction. The serial type inkjet
recording apparatus according to the present exemplary embodiment
is an example of the recording apparatus that can perform
multi-pass recording, in which the carriage performs scanning two
or more times in the same region of a recording medium to record an
image.
FIG. 17 is a see-through view illustrating an example of a
configuration of the serial type inkjet recording apparatus.
As illustrated in FIG. 17, a serial type recording head 1701
includes a first chip 1704 and a second chip 1705. The serial type
recording head 1701 is mounted on a carriage 1702, which can slide
relative to a shaft 1703. The serial type recording head 1701 can
perform recording when the carriage 1702 moves in the forward and
backward directions in the main scanning operation in a state where
the carriage 1702 is slidably supported by the shaft 1703.
Each of the first and second recording chips 1704 and 1705 includes
four recording element arrays that are disposed in parallel with
each other to constitute four rows A to D. The recording element
array that constitutes the row A can be used to perform recording
with a black ink. The recording element array that constitutes the
row B can be used to perform recording with a cyan ink.
The recording element array that constitutes the row C can be used
to perform recording with a magenta ink. The recording element
array that constitutes the row D can be used to perform recording
with a yellow ink. The first and second recording chips 1704 and
1705 are disposed in a predetermined relationship so as to be
partly overlapped with each other. A connected portion existing
between the first and second recording chips 1704 and 1705 is
similar in configuration to the connected portion illustrated in
FIG. 6.
FIG. 18 is a block diagram illustrating an example of a
configuration of a control system for an inkjet recording apparatus
according to the present exemplary embodiment. Compared to the
first exemplary embodiment, the control system according to the
present exemplary embodiment includes a pass mask storage unit
1004d and a pass separation processing unit 1006g, which can be
used to perform multi-pass recording. The rest of the configuration
illustrated in FIG. 18 is similar to the corresponding part of the
first exemplary embodiment described with reference to FIG. 9.
The pass separation processing unit 1006g performs processing for
separating the binary dot layout pattern generated by the connected
portion data distribution unit 1006f, using a pass mask stored in
the pass mask storage unit 1004d, into binary dot layout patterns
to be used for recording in respective passes.
The pass mask is a mask pattern constructed by binary (i.e., "1" or
"0") data. The binary dot layout pattern to be used for recording
in each pass can be generated by obtaining a logical AND of a
binary dot layout pattern to be recorded by each recording element
array and a pass mask. In the present exemplary embodiment, a pass
mask P1 can be used to generate an image in the first pass and a
pass mask P2 can be used to generate an image in the second pass
when the image recording apparatus performs two-pass recording.
Further, the pass masks P1 and P2 can satisfy the following
relationship. P1+P2=1 P1.times.P2=0 In the above-described
formulae, "+" represents a logical OR calculation and ".times."
represents a logical AND calculation.
The binary dot layout pattern to be used in the two-pass recording
can be generated by obtaining a logical AND of a binary dot layout
pattern to be recorded by each recording element array and a pass
mask in the following manner. The present exemplary embodiment uses
the following expressions to represent binary dot layout patterns
to be recorded by respective recording element arrays, which can be
generated by the connected portion data distribution unit
1006f.
More specifically, Out1_K, Out1_C, Out1_M, and Out1_Y represent
binary dot layout patterns to be recorded by the rows A, B, C, and
D of the recording chip 1704 illustrated in FIG. 17. Similarly,
Out2_K, Out2_C, Out2_M, and Out2_Y represent binary dot layout
patterns to be recorded by the rows A, B, C, and D of the recording
chip 1705 illustrated in FIG. 17.
As an example, the present exemplary embodiment indicates a method
for generating binary dot layout patterns Out1_K_1 and Out1_K_2 to
be recorded by the row A of the recording chip 1704 according to
the two-pass recording. Further, the present exemplary embodiment
indicates a method for generating binary dot layout patterns
Out2_K_1 and Out2_K_2 to be recorded by the row A of the recording
chip 1705 according to the two-pass recording.
Similarly, the present exemplary embodiment can generate binary dot
layout patterns to be recorded by the rows B, C, and D of the
recording chip 1704 according to the two-pass recording, as well as
binary dot layout patterns to be recorded by the rows B, C, and D
of the recording chip 1705 according to the two-pass recording,
using similar formulae. Out1.sub.--K.sub.--1=Out1.sub.--K.times.P1
Out1.sub.--K.sub.--2=Out1.sub.--K.times.P2
Out2.sub.--K.sub.--1=Out2.sub.--K.times.P1
Out2.sub.--K.sub.--2=Out2.sub.--K.times.P2 In the above-described
formulae, ".times." represents the logical AND calculation.
FIG. 19 is a flowchart illustrating an example of image data
processing according to the present exemplary embodiment. The
processing illustrated in FIG. 19, except for step S1907, is
similar to the processing according to the first exemplary
embodiment illustrated in FIG. 13.
In step S1907, the pass separation processing unit 1006g performs
processing for separating the binary dot layout pattern to be
recorded by each recording element array, which is generated in
step S1406, into binary dot layout patterns to be used in the
two-pass recording.
As described above, the image recording apparatus according to the
third exemplary embodiment can prevent or reduce undesirable
streaks from being generated in an image region corresponding to a
connected portion extending between two recording element arrays to
attain a goal of obtaining high-quality recorded images while
realizing speedy recording processing.
To generate the binary dot layout patterns to be used by respective
recording element arrays to perform recording in each pass, the
third exemplary embodiment distributes the binary dot layout
pattern generated by the binarization processing (see step S1405)
through two-step mask processing performed in steps S1406 and
S1907.
However, the above-described distribution processing can be
accomplished through single mask processing. In this case, to
eliminate streaks appearing in an image region corresponding to a
connected portion extending between two recording element arrays,
the present exemplary embodiment changes the pass masks (not the
connection masks) according to the gradation.
The reason why the above-described two-step mask processing can be
replaced with the single mask processing is described below with
reference to the third exemplary embodiment. Hereinafter, a method
for generating binary dot layout patterns to be recorded in
respective passes by the row A of the recording chip 1704 and the
row A of the recording chip 1705 that can record the K coloring
material is described below.
In the present exemplary embodiment, the row A of the recording
chip 1704 records the binary dot layout patterns Out1_K_1 and
Out1_K_2 according to the two-pass recording. Similarly, the row A
of the recording chip 1705 records the binary dot layout patterns
Out2_K_1 and Out2_K_2 according to the two-pass recording.
Further, in the connection mask "a", the connection mask "b", and
the connection mask "c" according to the third exemplary
embodiment, mask patterns M1_a, M1_b, and M1_c can be applied to
the row A of the recording chip 1704. These mask patterns M1_a,
M1_b, and M1_c correspond to the connection mask 804 illustrated in
FIG. 7. Similarly, mask patterns M2_a, M2_b, and M2_c can be
applied to the row. A of the recording chip 1705. These mask
patterns M2_a, M2_b, and M2_c correspond to the connection mask 805
illustrated in FIG. 7.
In the following description, Out_K represents a binary dot layout
pattern of the coloring material K, which is generated in step
S1405. For the sake of convenience, it is assumed that the binary
dot layout pattern Out_K has a size comparable to that of the mask
patterns M1_a, M1_b, M1_c, M2_a, M2_b, and M2_c. Further, the
binary dot layout pattern Out_K can be distributed to any one of
the connection mask "a", the connection mask "b", and the
connection mask "c" according to the gradation.
In the third exemplary embodiment, the binary dot layout patterns
Out1_K_1, Out1_K_2, Out2_K_1, and Out2_K_2 to be recorded according
to the two-pass recording can be obtained according to the
following formulae. In the following formula, P1 and P2 represent
the pass masks described in the third exemplary embodiment. For the
sake of convenience, it is now assumed that the mask patterns M1_a,
M1_b, M1_c, M2_a, M2_b, and M2_c are comparable in size.
(If the connection mask "a" is used)
Out1.sub.--K.sub.--1=Out.sub.--K.times.M1.sub.--a.times.P1
Out1.sub.--K.sub.--2=Out.sub.--K.times.M1.sub.--a.times.P2
Out2.sub.--K.sub.--1=Out.sub.--K.times.M2.sub.--a.times.P1
Out2.sub.--K.sub.--2=Out.sub.--K.times.M2.sub.--a.times.P2 (If the
connection mask "b" is used)
Out1.sub.--K.sub.--1=Out.sub.--K.times.M1.sub.--b.times.P1
Out1.sub.--K.sub.--2=Out.sub.--K.times.M1.sub.--b.times.P2
Out2.sub.--K.sub.--1=Out.sub.--K.times.M2.sub.--b.times.P1
Out2.sub.--K.sub.--2=Out.sub.--K.times.M2.sub.--b.times.P2 (If the
connection mask "c" is used)
Out1.sub.--K.sub.--1=Out.sub.--K.times.M1.sub.--c.times.P1
Out1.sub.--K.sub.--2=Out.sub.--K.times.M1.sub.--c.times.P2
Out2.sub.--K.sub.--1=Out.sub.--K.times.M2.sub.--c.times.P1
Out2.sub.--K.sub.--2=Out.sub.--K.times.M2.sub.--c.times.P2 In the
above-described formulae, ".times." represents the logical AND
calculation.
The following formulae are single mask patterns that aggregate two
mask patterns on the right side of the above-described formulae.
M1.sub.--a1=M1.sub.--a.times.P1 M1.sub.--a2=M1.sub.--a.times.P2
M2.sub.--a1=M2.sub.--a.times.P1 M2.sub.--a2=M2.sub.--a.times.P2
M1.sub.--b1=M1.sub.--b.times.P1 M1.sub.--b2=M1.sub.--b.times.P2
M2.sub.--b1=M2.sub.--b.times.P1 M2.sub.--b2=M2.sub.--b.times.P2
M1.sub.--c1=M1.sub.--c.times.P1 M1.sub.--c2=M1.sub.--c.times.P2
M2.sub.--c1=M2.sub.--c.times.P1 M2.sub.--c2=M2.sub.--c.times.P2 In
the above-described formulae, ".times." represents the logical AND
calculation.
Therefore, the binary dot layout patterns Out1_K_1, Out1_K_2,
Out2_K_1, and Out2_K_2, which are recorded according to the
two-pass recording in the third exemplary embodiment, can be
generated using the aggregate mask patterns in the following
manner.
(If the connection mask "a" is used)
Out1.sub.--K.sub.--1=Out.sub.--K.times.M1.sub.--a1
Out1.sub.--K.sub.--2=Out.sub.--K.times.M1.sub.--a2
Out2.sub.--K.sub.--1=Out.sub.--K.times.M2.sub.--a1
Out2.sub.--K.sub.--2=Out.sub.--K.times.M2.sub.--a2 (If the
connection mask "b" is used)
Out1_K.sub.--1=Out.sub.--K.times.M1.sub.--b1
Out1.sub.--K.sub.--2=Out.sub.--K.times.M1.sub.--b2
Out2.sub.--K.sub.--1=Out.sub.--K.times.M2.sub.--b1
Out2.sub.--K.sub.--2=Out.sub.--K.times.M2.sub.--b2 (If the
connection mask "c" is used)
Out1.sub.--K.sub.--1=Out.sub.--K.times.M1.sub.--c1
Out1.sub.--K.sub.--2=Out.sub.--K.times.M1.sub.--c2
Out2.sub.--K.sub.--1=Out.sub.--K.times.M2.sub.--c1
Out2.sub.--K.sub.--2=Out.sub.--K.times.M2.sub.--c2 In the
above-described formulae, ".times." represents the logical AND
calculation.
As described above, the binary dot layout patterns Out1_K_1,
Out1_K_2, Out2_K_1, and Out2_K_2 to be recorded according to the
two-pass recording can be generated by using the aggregated mask
patterns as pass masks. In other words, the above-described
two-step mask processing can be replaced with the single mask
processing.
An example of a configuration for realizing a fourth exemplary
embodiment of the present invention is described below. Similar to
the third exemplary embodiment, the fourth exemplary embodiment can
be realized by the serial type inkjet recording apparatus
illustrated in FIG. 17.
FIG. 20 is a block diagram illustrating an example of a
configuration of a control system for an inkjet recording apparatus
according to the fourth exemplary embodiment.
The configuration illustrated in FIG. 20 is different from the
above-described configuration according to the third exemplary
embodiment in that a pass mask storage unit 2001, a pass mask
information storage unit 2002, a pass mask selection processing
unit 2003, and a pass separation processing unit 2004 are provided.
The rest of the configuration illustrated in FIG. 20 is similar to
the corresponding part of the third exemplary embodiment described
with reference to FIG. 18.
The pass mask storage unit 2001 can store the above-described
aggregated mask patterns M1_a1, M1_a2, M2_a1, M2_a2, M1_b1, M1_b2,
M2_b1, M2_b2, M1_c1, M1_c2, M2_c1, and M2_c2.
The pass mask information storage unit 2002 can store information
representing the visibility of streaks appearing in an image region
corresponding to a connected portion extending between two
recording element arrays in a case where the aggregated mask
patterns are used to perform recording.
The pass mask selection processing unit 2003 can select a pass mask
for each coloring material to record an image that includes a
smaller amount of streaks in an image region corresponding to a
connected portion extending between two recording element arrays,
from the masks stored in the pass mask storage unit 2002, based on
an average value for each coloring material calculated by the
gradation information acquisition processing unit 1006c.
In this case, the pass mask selection processing unit 2003 can
refer to the information stored in the pass mask information
storage unit 2002 to determine the pass mask capable of recording
an image that includes a smaller amount of streaks in an image
region corresponding to a connected portion extending between two
recording element arrays.
The pass separation processing unit 2004 can separate the binary
dot layout pattern for each coloring material generated by the
binarization processing unit 1006e, using the pass mask stored in
the pass mask storage unit 2001, into binary dot layout patterns to
be used for recording in respective passes.
FIG. 21 is a flowchart illustrating an example of a procedure of
image data processing according to the present exemplary
embodiment. The processing flow illustrated in FIG. 21 is similar
to the processing flow described in the third exemplary embodiment
except that the connection mask selection processing step (step
S1404) is replaced by pass mask selection processing (step S2104)
and further the connected portion data distribution processing
(step S1406) and the pass separation processing (step S1907) are
aggregated into pass separation processing (step S2106).
As described above, the image recording apparatus according to the
fourth exemplary embodiment can prevent or reduce undesirable
streaks from being generated in an image region corresponding to a
connected portion extending between two recording element arrays to
attain a goal of obtaining high-quality recorded images while
realizing speedy recording processing.
In the above-described exemplary embodiment, the mask information
storage unit stores measurement results with respect to the
visibility of streaks appearing in an image region corresponding to
a connected portion extending between two recording element arrays,
which can be generated when a plurality of mask patterns stored in
the connection mask storage unit are used to record, with each
coloring material, a plurality of test image data that are
different in gradation.
However, the mask information storage unit can include a table
storing mask information selectable according to an average value,
instead of storing the measurement results. When a connection mask
is selected, the connection mask can be selected referring to the
table based on the average value.
The above-described exemplary embodiment uses an average value of
image data corresponding to the connected portion extending between
two recording element arrays as gradation information calculated by
the gradation information acquisition processing unit. The
gradation information can be any other value that represents the
density characteristics of image data corresponding to the
connected portion extending between two recording element arrays.
For example, the gradation information can be a weighted average
value that is weighted according to each region, a simply summed
value, a central value, or a gradation level (other than 0) that is
highest in frequency of occurrence.
The above-described configuration according to the second exemplary
embodiment, which uses multi-valued masks, can be applied to the
serial type inkjet recording apparatus described in the third
exemplary embodiment and the fourth exemplary embodiment.
Further, a computer can execute a program stored in a RAM or a read
only memory (ROM) thereof to realize each unit that constitutes the
recording apparatus according to the above-described exemplary
embodiments of the present invention.
It is useful to supply software programs, directly or from a remote
place, to a system or an apparatus, if the software programs can
execute each step of the above-described recording methods (i.e.,
the flowcharts illustrated in FIGS. 13, 16, and 19 in the
above-described exemplary embodiments). Then, a single or a
plurality of processors of the system or the apparatus can read and
execute the supplied program code to realize the present
invention.
In this case, an external apparatus can execute the processing for
determining binary data of each recording element array and all of
the preceding processing. The external apparatus can transfer the
determined binary data to a recording apparatus. The recording
apparatus can perform recording based on the transferred data.
Accordingly, when a recording apparatus performs the
above-described image data processing, the recording apparatus can
serve as an image processing apparatus according to an exemplary
embodiment of the present invention. When an external apparatus
performs the above-described image data processing, the external
apparatus can serve as an image processing apparatus according to
an exemplary embodiment of the present invention.
In the context of the present specification, the term "recording"
includes not only formation of meaningful information (e.g.,
characters, graphics, etc.) but also formation of any meaningless
information. The term "recording" further includes formation of an
image, a design, or a pattern on a recording medium, and includes
processing applied to a medium. Moreover, the term "recording"
includes formation of both visible and invisible information.
Further, the term. "recording medium" denotes a paper usable in a
general recording apparatus, a cloth, a plastic film, a metallic
plate, a glass plate, a ceramic member, a wood plate, a leather
sheet, or any other material that can absorb an ink.
While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is
not limited to the disclosed exemplary embodiments. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all modifications, equivalent structures, and
functions.
This application claims priority from Japanese Patent Applications
No. 2008-288967 filed Nov. 11, 2008 and No. 2009-244716 filed Oct.
23, 2009, which are hereby incorporated by reference herein in
their entirety.
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